Fast ignition driven by quasi-monoenergetic ions: Optimal ion type and reduction of ignition energies with an ion beam array

TL;DR

This study uses numerical simulations to identify optimal quasi-monoenergetic ion types and irradiation schemes that significantly reduce ignition energies in inertial fusion, highlighting the potential of intermediate Z ions and beam focusing.

Contribution

The paper introduces a new irradiation scheme combined with intermediate Z ions to drastically lower ignition energy requirements in fast ignition inertial fusion.

Findings

Ignition energies are nearly independent of ion atomic number but increase with Z^2.

Focusing ion beams into 10 μm spots enhances energy efficiency.

Using vanadium ions and the new scheme reduces required ions by about three orders of magnitude.

Abstract

Fast ignition of inertial fusion targets driven by quasi-monoenergetic ion beams is investigated by means of numerical simulations. Light and intermediate ions such as lithium, carbon, aluminium and vanadium have been considered. Simulations show that the minimum ignition energies of an ideal configuration of compressed Deuterium-Tritium are almost independent on the ion atomic number. However, they are obtained for increasing ion energies, which scale, approximately, as Z^2, where Z is the ion atomic number. Assuming that the ion beam can be focused into 10 {\mu}m spots, a new irradiation scheme is proposed to reduce the ignition energies. The combination of intermediate Z ions, such as 5.5 GeV vanadium, and the new irradiation scheme allows a reduction of the number of ions required for ignition by, roughly, three orders of magnitude when compared with the standard proton fast ignition scheme.